One method for examining the gastrointestinal tract for the existence of polyps and other clinically relevant features that may indicate regarding the potential of cancer is performed by swallowing an imaging capsule that will travel through the tract and view the patient's situation. In a typical case the trip can take between 24-48 hours, after which the imaging capsule exits in the patient's feces. Typically the patient swallows a contrast agent to enhance the imaging ability of the imaging capsule. Then the patient swallows the imaging capsule to examine the gastrointestinal tract while flowing through the contrast agent. The imaging capsule typically includes a radiation source, for example including a radioisotope that emits X-rays or Gamma rays. The radiation is typically collimated to allow it to be controllably directed toward a specific area during the imaging process. In an exemplary case the imaging capsule is designed to measure Compton back-scattering and transmits the measurements (e.g. count rate) to an external analysis device, for example a computer or other dedicated instruments.
In a typical implementation a radio-opaque contrast agent is used so that a position with a polyp will have less contrast agent and will measure a larger back-scattering count. Alternatively, other methods may be used to image the gastrointestinal tract.
U.S. Pat. No. 7,787,926 to Kimchy the disclosure of which is incorporated herein by reference, describes details related to the manufacture and use of such an imaging capsule.
Use of an imaging capsule exposes the user to radiation, which may be potentially harmful. Accordingly, it is of interest to limit the user's exposure to radiation when not necessary, for example while the imaging capsule is located in positions that do not need to be measured. Typically, the imaging capsule may be designed with shutters that can be instructed to block the exit of radiation when not needed. However, there still exists the hazard that in case of malfunction of the imaging capsule, for example in case of a power failure, radiation may be emitted without constraint.
It is thus desirable to design a fail-safe radiation blocking mechanism that automatically blocks the emission of radiation and only allows radiation to be emitted if power is available and the device provides an instruction to allow radiation to be emitted. It may be further desirable to provide such a mechanism that can save power when opening and closing the shutters.